Apparatus for manufacturing tires



Aug. 14, 1945. V KQVACS APPARATUS FOR MANUFACTURING TIRES Original Filed lay 25, 1942 3 Sheets-Sheet 1 I I n1 v INVENTOR- 564m Kama:

E374 BY 4, (%4

' ATTORNEY Aug. 14, 1945. KQVACS 2,382,069

' APPARATUS FOR MANUFACTURING TIRES Original Filed May 25,1942 5 Sheets-Sheet 2 -INVENTOR: fien/vx Kamca.

ATTORNEY.

Aug. 14, 1945. ev 3s APPARATUS FOR MANUFACTfiRiNG' TIRES Original Filed ua 25,1942 3 Sheets Sh eet a flvvtzvrba fen/v4 Kay/ms. 5 4

T ATTORNEY.

Patented Aug. 14, 1945 Frank Kovacs, Akron, Ohio, assignor to Seiberl ing Rubber Company, Barberton, Ohio, a corporation of Delaware Original application May 25, 1942, Serial No. 444,439. Divided and this application June 26, 1944, Serial No. 542,206

4 Claims. (Cl. 164-86) This invention relates to pneumatic tire structures of vulcanized rubber or the like and, in particular, relates to apparatus for producing the same. This application is a division of application Serial No. 444,439, filed May 25, 1942.

Heretofore, new or unwom tires, in general, have had satisfactory characteristics in regard to stopping ability and traction. Diiferences in these characteristics may be found in various type of new tires, depending on design, but such diiferences' are slight. It is possible to obtain improved antiskid and traction qualities in such new or unwom tires by various slitting and other tread alterations, but-in the past this has been accomplished usually at the expense of obtaining other undesirable characteristics, such as noise, uneven tread wear, tread cracking, etc.

Most present-day low-pressure balloon tires have one or more continuous circumferential ribs,

which upon wearing down naturally become more stiff or less flexible, and because of this stiffening of the ribs, stopping and traction values of the tire are materially reduced. The more the tread wears down, the most rigid the ribs become; and,

consequently, the less the stopping and traction value becomes.

In the past, conventional tires have been provided with transverse slits or cuts in the continuous ribs thereof, but these cuts have usually extended from the ground-engaging surfaces of the ribs to the full depth of the grooves defining said ribs. Such constructions, however, have been found to be noisy and to wear irregularly. In other words, there is too much flexibility in the ribs in the early stages of tread wear. given rise to a suggestion by a prior patentee to cut slits in the ribs which are only about onethird the depth of the grooves and then to re-slit the tire in this manner after it has become worn to such an extent that the original slits are no longer eifective.

A purpose of this invention is to provide an improved tire having one or more continuous ribs, said tire being so constructedas to give the usual desirable characteristics of the new or unworn tire, but providing ribs in such tires with slits or openings therein which do notbecome effective until the tire is substantially worn and then which provide flexibility in the worn ribs to continue substantially throughout the life of the tire, the desirable characteristics of traction, antiskid, uniform tread wear, silence, etc., usually present in the new and unwom tire.

Stated in another way, a purpose of the invention is to provide a tire structure of the character This has described which does not require renovation as it wears and in which the continuous ribs thereof have slits or openings arranged therein in such a manner that excessive flexing of the ribsis obviated at all stages of tread Wear, whereby the strain on the rubber at the base of the slits, for example, caused by long continued flexing of the ribs, will not tear the rubber inwardly of the slits, through the tread, and 'into' the carcass and thereby result in premature failure of the tire.

Another object of the invention is to provide a simple, eflicient, and practical apparatus for producing transverse slits of substantially uniform depth in tire structures of the characterdescribed havingtransversely curved'tread surfaces;

These and other objects of the invention will be manifest from the following brief description and the accompanying drawings.

Of the, accompanying drawings: Fig. 1 is an edge view of a portion of a pneumatic tire embodying the invention;

Fig. 2 is a transverse cross-section taken on line 2-2 of Fig. 1;

Fig. 3 is a cross-section taken on line 33 of Fig.1; Y

Fig. 4 is a view similar to Fig. 3 illustrating the tread after it has become substantially worn; L Fig. 5 is a plan view of apparatus for'manufacturing pneumatic tires in accordance with the invention: I, r Fig. 6 is a front elevation thereof;

Fig. 7 is a front detail view of a slitting tool used with the apparatus shown in Figs. 5 and 6;:

Fig. 8 is a side view of the tool shown in Fig. '7; Fig. 9 is a cross-section taken substantially on line 99 of Fig. 5; and

Fig. 10 is a side elevation of a portion of tire structure shown in Figs. 1 and 2.

Referring to the drawings, a tire embodying the invention is illustrated in Figs. 1 to 4,- inclusive. The tire shown is a standard type on the market and comprises the usual carcass constructiOn III on which is a tread l I formed witha series of grooves I2, I 2 so formed and spaced as to divide the tread into a plurality of continuous ribsl3, l3 having serrated or saw-tooth nonskid edges. The depth of the grooves l2, or height of the ribs l3, and-the width of the ribs determined by the spacing of the grooves, are such that the tread in a new tire will have a high degree of flexibility and wiping action, and the sharp or serrated edges of the ribs will afford ample traction'and nonskid qualities. The tread will wear uniformly and will be substantially noiseless in its operation.

But as such a tread wears down, the ribs I3 beshown,

come less and less flexible, and, in accordance with the present invention, these ribs are slitted as indicated at I4. In the specific embodiment these slits l4, 14 extend completely through all of the ribs of the tread from one side or shoulder of the tread to the other. The slits preferably are of the order of two-thirds of the height of the ribs from the outer or wearing sur-' face of the tread. The slits l4 have no effect whatever upon the normal operation of the tire they would otherwise be too stiff and inflexible to provide the desired tread characteristics. The

@produced by various procedures, either during or upon its usual tread characteristics untilthe tread has worn down one-third of theheight of the ribs, whereupon the slits l4 become effective and divide the worn ribs into a plurality of separate blocks which provide for suflicient flexibility to maintain substantially the original tread characteristics of the new or unworn tire.

It is to be understood that in -tires of different types with different treads and utilizing different compo nd theremavbe variation inth h i of the slits l4 and that these may extend down into the tread inwardly of theibottoms of the groove l2, such changes OrQmodifiCati -n being contemplated by the present inventorfand being chan es in. degree within the spirit of the present invention. a

The invention may be embodied in niany types of tires and in many different-arrangements.

For example, slits corresponding to'theslits .14 in Figs. 1 to 4 may be formedin the'tread so; as

to extend through ribs from the opposite sides or shoulders toward the center a d are no caused to pass through the center rib, which may be left continuous throughoutflits height. The breaking up of the side ribs into separate blocks by means of the slitsmaybe ample {to maintain substantially the desirablecharacteristics of the tread throughout the life of the tire or until the tread haxsbeencompletely worn away.

v 111.. In another form of the inventiom in a tire formed with continuous -ribs,- slits corresponding to slits M are formed through the ribsfrom opposite sides or shoulders of the'tire in staggered relationship. is variation whieh will be immediat ly underst d by; s illed arti a since nonskid format-ions (if-variou types are frequently staggered on opposite sides;-.;of= the tire. f I In a'tire havin a t ead compri in centra circumferential ribs and: side nonsk-idblocks Which are circumierentially discontinuous, the

slits may be extended through the; ribs from the side or shoulders of the tire-inany-suitable manthe vulcanizationthereof or subsequently, and by the use of many different types of equipment.

The preferred procedure consists in forming the slits in the tread of the tire after vulcanization by flattening the tread and causing one or more knives to pierce the flattened tread from one side to the other thereof or inwardly from opposite sides of the tire toward the center, as may be desired or required.

Suitable procedure and equipment for this purpose are illustratedin Figs, 5 to 1Q, ino111sive.

* This equipment comprises. a clamping. device .68

er and in, doing so, maybe ex ended through any portion of the sideprojections which, is raised on the tread, The slits v wiliathus provide the desired action infthe ribs an: will not substantially affect the normal operatiq of he side nonskid blocks. 7 7 r y, In tires fo med with cen aln s id Proieetions which are circumferentially discontinuous and w ontinu us ri s n he hou1.d@ ..;th ribs may be slit without altering the ;;central nonskid projections. 1 It will be understood that in all forms of the nve ti n as disclosed, n the ab v 'na agraphs and as s w in the figur s ofritlie r w n s referred to, the-ribs are'slit substantially in "the manner ind cated inFigs. 2; 3, and if 0t slits in all oi th se tir s d n t-become 'efi until there has been a substantial. wea fie f' th having a base portion fifl thelatter having a fixed upright 10 at on nd," and ablocls. lit slidably mounted in a U-shaped ineirrber112 fixed on the other end thereof to'be shiitabletowardand from upright 10. The tire l0, for example, shown in Figs. 1 to 4, inclusive, andFig; may. be placed between the upright 10 and the shiftable block H, said tire first being mounted on-a rim R and inflate by means of. an nner tube .A. y ans f a ank Iii-hav ng a: portion!! t read d hrou h a ssp o l onmember :13, the inner end of the threaded, portion 14 is en s eeabie with the-slidebloek H- for urgin .h same toward the fixed upright 10. By turning t e c an 1,3,v p e sur is. a lied at. diametricany opposi points of he tire to..-flatten;out: asubr d po n h reofhat the. point where it :is urged a st, a flat-i n r surface-"m of upr ht Mounted on a plate 15- seoured'to the; upright Til may be a block, havinga yertical'ly extending squared recess 11 slightly inwardiyi'ofiface m of the upright 10 for reoeiving ar s'qua'red stem 78 of ai slitting toolllflpsaid tool having a blade 8| secured to thelowerl-end' of stem 18, and having a suitable handle fli. Theblade 8| of tool 80 may be relatively fiat and of such proportions, as best shown in Figs. '3 and 4-,"f or forming-slits of desired size in the tire I0. By means of handle 82, the tool-80 maybe urged downwardly in openings 'l'l to-pierce blade 8 transversely through the tread'portion il of the tire It, the arrangement being such that the blade forms a transverse slit l4 through the tread in a' plane substantially at'a'90 angleto the ground-engaging surface of tire, C(See Figs. 6 and the outer edge of theslit 1'4 preferably being inwardly of the flat surface, lll 'of upright 10, a distance equivalent "to. about one th rd th e t of'the ire r'i l a p v ouslv de an por n. ofgthe norm ly urved; outer ri A e s of .oircumierenti lly space sl s the transverse ourvaturekof the tire.section, las

best shown in 2. With-she i fii i-fioatiens, the apparatus ;sl iqwn;anddescribedmay be 1.1111

ized for forming a plurality of slits in the tire with a single stroke of the slitting tool.

It is to be understood that by means of apparatus substantially as described the slits l4 may be formed to extend at various angles to the ground-engaging surface of the tire. Similarly, the slits may be of varying depths at different points between the tire shoulders, or the outer edges of the slits may be at varying distances from the ground-engagin surface of the tread to vary the amount of flexibility required at different points in the tread as may be desired in certain tread designs. Also, the slits may be extended through tread portions of the tire at angles to transverse radial planes through the tire.

Thus has been provided an improved tire construction and apparatus for manufacturing the same. The continuous outer portions of the ribs give the new or substantially unworn tire the same characteristics as a standard unslit tire. As the tread wears down, however, which stiffens the ribs, the transverse slits or openings of the improved tire become exposed at the ground-engag' ing surfaces of the ribs, providing additional nonskid edges and worn-rib flexibility to maintain the fore mentioned desirable characteristics in the tire.

Modifications of the invention may be resorted to without departing from the spirit thereof or the scope of the appended claims.

What I claim is:

1. Apparatus for slitting pneumatic tire tread comprising a support for supporting a tire, means on said support operable to apply pressure against the tread surface of a tire supported thereon to flatten an area of the tread, a rectilinear cutter, and means for mounting said outter to be shiftable to provide a transverse slit through said flattened area of the tread.

2. Apparatus for slitting pneumatic tire treads, comprising a support for supporting a tire, means including a member shiftable against .the tread surface of a tire on said support to flatten an area of the tread, an element adjacent,

said shiftable member and transversely shiftable toward and from said tire, a rectilinear cutter mounted on said element, and means for shifting said element to move said cutter to provide a transverse slit or slits in the tire tread at said flattened area.

3. Apparatus for slitting pneumatic tire treads comprising a support for supporting a tire, a relatively fixed anvil on said support having a flat surface to be substantiallyat right angles to the plane of a tire mounted on said support, means on said support operable relatively to urge a tire on the support against said anvil to flatten an area of the tire tread against said flat surface, an element mounted in association with said anvil to be shiftable in the direction of the plane of transverse slit or slits in the tire tread at said flattened area thereof.

4. Apparatus for slitting pneumatic tire treads comprising a support for supporting a tire, a relatively fixed anvil on said support having a flat surface to be substantially at right angles to the lane of a tire mounted on said support, means on said support operable relatively to urge a tire on the support against said anvil to flatten an area of the tire tread against said flat surface, an element mounted in association with said anvil to be shiftable in the direction of the plane of said flat surface of the anvil, a rectilinear. cutting blade on said element to be shiftable in spaced relation to said fiat surface of the anvil for cutting a transverse slit or slits in the tire tread at said flattened area beneath the tread surface thereof.

FRANK KOVACS. 

